\subsection{不可求积可抵消}

	\begin{ti}
		求 $\int \frac{2x + 1}{x^{2}} \ee^{-2x} \dd{x}$.
	\end{ti}

	\begin{ti}
		求 $\int \frac{x + \sin x}{1 + \cos x} \dd{x}$.
	\end{ti}

	\begin{ti}
		求 $\int_{0}^{2} \frac{x \ee^{x}}{(1 + x)^{2}} \dd{x}$.
	\end{ti}

	\begin{ti}
		$\int \ee^{x} \bigl( \frac{1 - x}{1 + x^{2}} \bigr)^{2} \dd{x} = $\htwo.
	\end{ti}